2. Earth’s atmosphere as seen from space Photo: NASA

4.  78 % Nitrogen  21 % Oxygen  1 % Argon and other trace gases

5.  Troposphere ◦ Most of our weather occurs in this layer closest to the Earth’s surface  Stratosphere ◦ Where ozone (O 3 ) absorbs harmful UV radiation from the Sun and prevents it from reaching Earth’s surface

6.  Atmosphere contains the air we breathe  Protects us from the Sun’s radiation  Keeps Earth balanced  traps and releases heat  Atmospheres of other planets are different ◦ Mars  very thin atmosphere made of mostly CO 2 ◦ Venus  denser and hotter than Earth’s atmosphere ◦ Jupiter  large, turbulent atmosphere made of H and He

8.  Fossil fuels are fuels formed by natural resources such as anaerobic decomposition of buried dead organisms.  Fossil fuels are non-renewable resources because they take millions of years to form, and reserves are being depleted much faster than new ones are being made.

9.  We burn fossil fuels to produce useful energy  This fuel provides gas for our cars, electricity for our homes, and runs factories and powerplants

10.  The burning of fossil fuels produces around 21.3 billion tons (21.3 gigatons) of carbon dioxide (CO 2 ) per year

12.  A type of air pollution that comes from internal combustion engines and industrial fumes that react with sunlight to form photochemical smog  The word ‘smog’ comes from a combination of smoke and fog  Mixture of air pollutants, including gases and particles that are too small to see  Smog is also caused by large amounts of coal burning in an area caused by a mixture of smoke and sulfur dioxide

13.  Type: Particulate Matter - or PM. This is the name given to microscopic particles that pollute the air. They vary in size and chemical make-up. Sources: Industrial and vehicle emissions, road dust, agriculture, construction and wood burning.  Type: Ground-level Ozone. This gas is the result of a chemical reaction when certain pollutants are combined in the presence of sunlight. Ground-level ozone shouldn't be confused with the ozone layer in the sky, which protects us from ultraviolet radiation. Sources: Ground-level ozone comes mostly from burning fossil fuels for transportation and industry. Ozone levels peak between noon and 6 p.m. during the summer months.

14.  Type: Sulfur dioxide Sources: Coal-fired power plants and non-iron ore smelters  Type: Carbon monoxide Sources: Mostly from burning carbon fuels (e.g. motor vehicle exhaust)

17.  Acid rain is a rain or any other form of precipitation that is unusually acidic (has a low pH)  Acid rain is caused by emissions of sulfur dioxide and nitrogen oxides which react with the water molecules in the atmosphere to produce acids

19.  Asthma  Lung Cancer  Can cause coughing, chest pains, throat irritation  Colds and pneumonia

20.  Can damage buildings and historic monuments, especially those made of rocks such as limestone and marble containing large amounts of calcium carbonate  Soil biology and chemistry can be damaged because microbes cannot tolerate changes in pH  As lakes and river become more acidic, biodiversity is reduced ◦ Because of low pH, fish eggs may not hatch and some adult fish are killed ◦ Eliminates insect life and some fish species (brook trout)

23.  Founded in 1990 by US Environmental Protection Agency (EPA)  Goal is to reduce overall atmospheric levels of sulfur dioxide and nitrogen oxides, which cause acid rain.  The program is an implementation of emissions trading that targets coal-burning plants, allowing them to buy and sell emission permits.

24.  There are several options for reducing SO 2 emissions, including using coal containing less sulfur, washing the coal, and using devices called “scrubbers” to chemically remove the SO 2 from the gases leaving the smokestack  Powerplants can use different fuels  burn natural gas instead of coal

25.  Nuclear power  Hydropower  Wind energy  Geothermal energy  Solar energy

26.  Takes many years for ecosystems to recover from acid rain even after emissions are reduced and rain pH is back to normal  “Liming” = a process in which limestone or lime is added to acidic lakes to cancel out the acidity ◦ Disadvantage: expensive and short-term solution

27.  Reducing and controlling the emissions from powerplants and cars  Implement cost-effective mechanisms to reduce emissions

28.  Turn off lights, computers, and other appliances when you're not using them.  Use energy-efficient appliances: lighting, air conditioners, heaters, refrigerators, washing machines, etc. For more information, see EPA’s ENERGY STAR Program.EPA’s ENERGY STAR Program.  Only use electric appliances when you need them.  Keep your thermostat at 68°F in the winter and 72°F in the summer. You can turn it even lower in the winter and higher in the summer when you are away from home.  Insulate your home as best you can.  Carpool, use public transportation, or better yet, walk or bicycle whenever possible  Buy vehicles with low NO x emissions, and properly maintain your vehicle.  Be well informed.

30.  Gases which absorb and emit radiation  Greenhouse Gases (GHG): ◦ Water Vapor ◦ Carbon Dioxide ◦ Methane ◦ Nitrous Oxide ◦ Ozone ◦ Chlorofluorocarbons (CFCs)

31.  The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions  The greenhouse effect keeps our planet warm  If we had no atmosphere, our Earth would be 32°C colder than it is today

37.  Plants need CO 2 to survive, and plants exposed to more CO 2 could grow up to 50% faster than normal  Increased global temperature due to greenhouse effect

44.  Treaty signed in which banned the use of CFCs and HFCs